Isogram Not Working As Expected

// Fill out your copyright notice in the Description page of Project Settings.
#include "BullCowCartridge.h"


void UBullCowCartridge::BeginPlay() // When the game starts
{
	Super::BeginPlay();
    SetupGame();
}

void UBullCowCartridge::OnInput(const FString& Input) // When the player hits enter
{
    if (bGameOver == true)
	{
		ClearScreen();
		SetupGame();
	}

	else
	{
		ProcessGuess(Input);

	}
}

// Check if isogram
// Check right number of characters
// Remove life
// If all lives lost, prompt for guess again
	// Show lives left
// Else print game over and HiddenWord
	// Prompt to play again, Press enter to play again?
	// If  yes, set hidden word and lives
	// Else quit game

void UBullCowCartridge::SetupGame()
{
	HiddenWord = TEXT("machine");
	Lives = HiddenWord.Len();
	bGameOver = false;
	PrintLine(TEXT("Welcome To Bull Cow Game")); //Prints Welcome Message
	PrintLine(TEXT("The HiddenWord Is %i Charecters Long"), HiddenWord.Len()); //remove the hardcoded 4 later
	PrintLine(TEXT("Type in your guess and \npress enter to continue..."));
	PrintLine(TEXT("You Have %i Lives"), Lives);
}

void UBullCowCartridge::EndGame()
{
	bGameOver = true;
	PrintLine(TEXT("Press Enter To Play Again"));
	
}
bool UBullCowCartridge::isIsogram(FString word)
{
    for(int i = 0; i < word.Len() - 1; i++)
    {
        if (word.IsValidIndex(i + 1))
        {
            if (word[i] != word[i + 1])
            {
                return false;
            }  
        }
    }

    return true;
}
void UBullCowCartridge::ProcessGuess(FString Guess)
{

    // Check if the PlayerGuess is the HiddenWord

    if (Guess == HiddenWord)
    {
        // The Player wins the game

        ClearScreen();

        PrintLine(TEXT("You guessed the word!"));

        PrintLine(TEXT("The hidden word is: %s."), *HiddenWord);

        PrintLine(TEXT("YOU WIN!"));

        EndGame();

        return;

    }

    if (Guess != HiddenWord)
    {

        // Clear terminal

        ClearScreen();

        // Print messages for the player telling about the mistake in the guess

        PrintLine(TEXT("Ooh sorry your guess is not correct! Hint:The hidden word has %i letters."), HiddenWord.Len());

        // Remove a life since the player missed in the guess

        PrintLine(TEXT("You lost a life. Now you have %i lives."), --Lives);

        if (Guess.Len() != HiddenWord.Len())
        {

            PrintLine(TEXT("Please remember that\nthe hidden word has %i letters."), HiddenWord.Len());

        }

        if (!isIsogram(Guess))
        {
            PrintLine(TEXT("This word has repeating letters!"));
        }

        if (Lives == 0)
        {
            PrintLine(TEXT("The Hiddenword was %s"), *HiddenWord);
            PrintLine(TEXT("Press Enter To Play Again"));
            EndGame();


        }
        

    }

}

This Is CPP File, The issue is that even though I enter an isogram
it is printing and treating it as it is not, I use UE5 beta. But from what I know this cannot be causing any issues though I have not tried it on UE4.

The Header File:

// Fill out your copyright notice in the Description page of Project Settings.

#pragma once

#include "CoreMinimal.h"
#include "Console/Cartridge.h"
#include "BullCowCartridge.generated.h"

UCLASS(ClassGroup=(Custom), meta=(BlueprintSpawnableComponent))
class BULLCOWGAME_API UBullCowCartridge : public UCartridge
{
	GENERATED_BODY()

	public:
	virtual void BeginPlay() override;
	virtual void OnInput(const FString& Input) override;
	void SetupGame();
	void EndGame();
	void ProcessGuess(FString Guess);
	bool isIsogram(FString Word);

	// Your declarations go below!
	private:
	
	FString HiddenWord;
	int32 Lives;
	bool bGameOver;
	
};

That is not an incorrect implementation of IsIsogram for two reasons

  1. if (word[i] != word[i + 1])
    {
        return false;
    }  
    
    The condition here is checking the wrong thing. If the word is “planet” then this does 'p' != 'l' which is true and the function would incorrectly return false. If you change it to == then.
  2. This only checks adjacent characters so would only work if the word is in sorted order. For the word “radar” which isn’t an isogram it would check the following
    r == a
    a == d
    d == a
    a == r
    
    And incorrectly report “radar” to be an isogram when it is not.